It is given that the quadrilateral WXYZ is a parallelogram.
By property of parallelogram the adjacent angles are supplementary so it follows:
[tex]\begin{gathered} \angle W+\angle Z=180 \\ 18b-11+9b+2=180_{} \\ 27b=189 \\ b=7 \end{gathered}[/tex]
Since the value of b is 7, the angle Z is given by:
[tex]\angle Z=9b+2=9(7)+2=65^{\circ}[/tex]
Hence b=7 and angle Z is 65 degrees.
